Assessments show Gichigami's whitefish & lake trout doing well
By Bill Mattes, GLIFWC Great Lakes Biologist
Odanah, Wis.—Gichigami (Lake Superior)—It is that time of year when namaycush (lake trout) and adikameg (whitefish) gather on spawning reefs out in Gichigami. GLIFWC, Bad River, Red Cliff and Keweenaw Bay fisheries crews all head out to set gill nets on known spawning reefs to assess the health of spawning populations by collecting biological information from lake trout and whitefish.
In addition, Keweenaw Bay staff collect eggs and milt to combine and fertilize so that lake trout can be raised in their hatchery and later released into on-reservation waters of Lake Superior.
Whitefish are the backbone of the commercial fishery on Lake Superior, and lake trout, largely a by-catch, are also sought after by the restaurants and fish markets around the region. Whitefish have been doing very well in Lake Superior. Fishery harvest, biological assessments, and population modeling all indicate that whitefish continue to do well with many young whitefish showing up in the populations.
Lake trout are also doing well according to assessments and population modeling. Their numbers have dipped slightly in waters less than 240 feet in recent years after bouncing back to near their 1929-1940 average. However, lake trout numbers remain more than sufficient to provide for commercial and recreational fishing and to suppress rainbow smelt.
Rainbow smelt are an invasive species that competes with and preys upon (eats) young cisco (a.k.a. lake herring) and whitefish. Lake trout keep rainbow smelt numbers in check by eating them. Lake trout in turn are the primary prey of sea lampreys. Therefore, large numbers of lake trout buffer the effects sea lampreys would have on other species, like whitefish and cisco.
Siscowet, a deepwater form of lake trout that is less desirable to the commercial and recreational fishery, are a large player in the fish community of Lake Superior too. Siscowet live primarily in waters greater than 240 feet deep—which is 70% of Lake Superior!
However, they have been showing up in larger numbers in water less than 240 feet in more recent years. This fall several were captured hanging around spawning reefs. Although they were not spawning, their presence is noteworthy. It is thought that this movement inshore is mainly because the siscowet population in the lake has increased. Siscowet are also food for lampreys, so they have benefited from lamprey control and in turn serve as a buffer to lamprey predation on other fish. Siscowet primarily feed on kiyi, bloater chubs, and deepwater sculpin. When venturing shallower, they will eat the same things as lake trout—i.e. cisco and rainbow smelt.
Lake Superior's fish community is bountiful and provides food and employment for many tribal members, and with continued cooperative management among all agencies, the future of Gichigami's fishery looks promising.
